Process for the preparation of alkylimidazolidone (meth)acrylates

ABSTRACT

The invention relates to a process for the preparation of alkylimidazolidone (meth)acrylates, generally expressed as compound (I):                    
     that are prepared by reacting at least one (meth)acrylate of formula (II):                    
     with a heterocyclic alcohol of formula (III):                    
     in the presence of a catalyst comprising at least one compound (a) which is a chelate formed of lithium and of a 1,3-dicarbonyl compound. The invention also relates to a composition comprising compound (I) in solution in (meth)acrylate (II). Finally, the invention involves the use of the abovementioned composition in the preparation of polymers that can be used as coatings and adhesives, in the treatment of paper and of textiles, as agent for leather treatment and in the production of paints with high wet adhesion characteristics.

FIELD OF THE INVENTION

The present invention relates to a process for the preparation ofalkylimidazolidone (meth)acrylates.

BACKGROUND

Alkylimidazolidone acrylates and methacrylates are known for their rolein the constitution of polymers which can be used as coatings andadhesives, in the treatment of paper and of textiles, for their use asagents for leather treatment and in the production of emulsion paints.

European patent application No. 236 994 relates to the preparation ofesters of (meth)acrylic acid by reacting an alkyl (meth)acrylate with aheterocyclic alcohol in the presence of a catalyst that is a titaniumalkoxide or a titanium, zirconium, iron or zinc chelate, combined with a1,3-dicarbonyl compound, which may be a metal chelate of a 1,3-diketone,in particular an acetylacetonate.

Such a catalyst has the major disadvantage of generating intenselycoloured products.

European patent application No. 433 135 relates to a process for thesynthesis of an alkylimidazoline (meth)acrylate, in which an alkyl(meth)acrylate is reacted with a heterocyclic alcohol in the presence ofa catalyst chosen from dialkyl tin oxides, dialkyl tin dialkoxides anddialkyl tin diesters.

Such a catalyst requires high reaction temperatures and often causesviolent polymerizations with formation of a very hard expanded polymer.

European patent application No. 453 638 also relates to the synthesis ofan alkylimidazoline (meth)acrylate in the presence of dialkyl tin oxide.

The subject of European patent application No. 571 851 is a process forthe preparation of alkylimidazoline (meth)acrylate, bytransesterification of an alkyl (meth)acrylate by means of aheterocyclic alcohol, in the presence of a catalytic system which is acombination of a catalyst based on lithium, for example in oxide,alkoxide, acetate, chloride or bromide form, and a catalyst based oncalcium, such as calcium oxide.

European patent application No. 619 309 relates to the preparation ofalkylimidazoline (meth)acrylate by reacting an alkyl (meth)acrylate witha heterocyclic alcohol in the presence of a catalyst chosen from thechelates of calcium with 1,3-dicarbonyl compounds, such as calciumacetylacetonate. The products obtained by the process described in thatdocument has an excessively strong colour.

Finally, European patent application No. 902 017 mentions the use of acatalyst that may be lithium, lithium carbonate or lithium hydroxide inthe preparation of a monomer from, in particular,hydroxyethyloxazolidine and methyl methacrylate.

However, the use of such catalytic systems does not make it possible tosimultaneously achieve the following main objectives:

a high conversion of the heterocyclic alcohol;

a low content of by-products;

a high kinetic;

a low thermal level; and

a faint colouring of the final product.

The subject of the invention is a process for the preparation ofalkylimidazoline (meth)acrylate, a process which makes it possible toachieve the objectives mentioned above.

Specifically, the subject of the invention is a process for thepreparation of compound (I):

wherein:

R¹ is a hydrogen atom or a methyl group; and

A and B represent, independently of each other, a straight- orbranched-chain alkylene group having from 2 to 5 carbon atoms;

by reacting at least one (meth)acrylate (II):

 wherein:

R¹ has the abovementioned meaning; and

R² is a straight- or branched-chain alkyl group having from 1 to 4carbon atoms;

with a heterocyclic alcohol (III):

 wherein A and B have the abovementioned meanings;

in the presence of a catalyst comprising at least one compound (a) whichis a chelate formed of lithium and of a 1,3-dicarbonyl compound.

The subject of the invention is also a composition comprising compound(I) obtained by the process according to the invention in solution in(meth)acrylate (II).

Finally, the subject of the invention is also the use of theabove-mentioned composition in the preparation of polymers that can beused as coatings and adhesives, in the treatment of paper and oftextiles, as agent for leather treatment and in the production of paintswith high wet adhesion characteristics.

DETAILED DESCRIPTION

The preparation process according to the invention, as has beendescribed above, makes use of a catalyst comprising at least onecompound (a) which is a chelate formed of lithium and of a1,3-dicarbonyl compound.

Examples of 1,3-dicarbonyl compounds include but are not limited to thefollowing:

a β-ketonic acid ester, such as acetylacetic ester;

a 1,3-diketone, such as acetylacetone, 3-methylacetylacetone,benzoylacetone, dibenzoylmethane, 2,4-hexanedione, 3,5-heptanedione,3-phenylacetylacetone, 4,4,4-trifluoro-1-phenyl-1,3-butanedione,2,2,6,6-tetramethyl-3,5-heptanedione,1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione and1,1,1-trifluoro-2,4-pentanedione.

Lithium acetylacetonate is most particularly preferred as compound (α).

Examples of reagent (II) include, but are not limited to, methyl, ethyl,n-propyl, isopropyl, n-butyl and isobutyl acrylates and methacrylates.

Preferably, reagent (II) is methyl methacrylate or acrylate.

An example of reagent (III) is 1-(2-hydroxyethyl)imidazolidyl-2-one,among others.

The quantity of compound (a) used for carrying out the process accordingto the invention is usually defined relative to the quantity ofheterocyclic alcohol.

Thus, the molar ratio of compound (a) to the heterocyclic alcohol (III)is generally between 0.05 and 0.3 percent, and preferably between 0.05and 0.15 percent.

In an advantageous variant of the process according to the invention,compound (a) is not used alone as catalyst, but rather in the form of amixture together with a second compound (b). Computer (b) may be chosenfrom magnesium alkoxides, sodium alkoxides, calcium alkoxides, calciumacetylacetonate, calcium oxide and calcium hydroxide.

As alkoxides, examples include methoxides, ethoxides, propoxides,isopropoxides, butoxides and isobutoxides.

With regard to the quantity of compound (b), it may be less than that ofcompound (a).

Typically, the quantity of compound (b) is chosen such that the molarratio of compound (b) to the heterocyclic alcohol (III) is between 0.01and 0.1 percent, and preferably between 0.01 and 0.05 percent.

The reaction between reagent (II) and reagent (III) is generally carriedout in the presence of an excess of either of these reagents.

It is, however, preferable to use more of reagent (II) than reagent(III).

Thus, it is desirable that the molar ratio of the (meth)acrylate (III)to the heterocyclic alcohol (III) is greater than 1, preferably between1.1 and 7, more preferably between 2 and 5.

In this manner, a composition comprising a solution of compound (I) in(meth)acrylate (II) is obtained as the product of the reaction, forexample:

a solution of 1-ethylimidazolidyl-2-one acrylate in methyl acrylate; oralternatively

a solution of 1-ethylimidazolidyl-2-one methacrylate in methylmethacrylate.

Such a composition, which has a colour of less than 100 APHA, may beadvantageously used directly in certain applications such as themanufacture of paints with high wet adhesion characteristics, thetreatment of leather or the manufacture of coatings.

The process according to the invention may be carried out in thepresence of one or more polymerization inhibitors, which may be chosenfrom phenothiazine, hydroquinone, the monomethyl ether of hydroquinone,di-tert-butyl-para-cresol, para-phenylenediamine, TEMPO(2,2,6,6-tetramethyl-1-piperidinyloxy) and di-tert-butylcatechol.

These compounds may be optionally combined with metal chelators such asEDTA, oxalic acid or the products marketed under the trademark VERSENEX.

The content of polymerization inhibitor is generally between 0.05 and0.5%, this percentage being expressed as weight of inhibitor (to whichthe weight of the associated chelator(s) is added where appropriate)relative to the weight of heterocyclic alcohol (III).

Regarding the operating conditions, the process is usually carried outat a temperature of between 70 and 120° C., and preferably between 85and 100° C., in liquid medium.

The pressure is in general at most equal to 1 bar; it is typicallybetween 0.3 and 1 bar.

It is advantageous to carry out the reaction with bubbling air.

The duration of the reaction depends on the operating conditions and theactivity of the catalyst. It is generally between 6 and 11 hours.

The reaction is desirably carried out in an anhydrous medium in order toavoid the deactivation of the catalysts.

The water present in the reagents is preferably removed by distillationin the form of an azeotrope of (meth)acrylate (II) and water.

The procedure may be briefly described as follows.

A mixture of the reagents (II) and (III) and of the inhibitor(s) isheated under reflux, while adjusting the pressure in the installation sothat the temperature in the reactor is maintained between 85 and 100° C.

The column is stabilized by introducing one or more polymerizationinhibitors at the top of the column, in the reflux.

The water present in reagents (II) and (III) and the inhibitor isremoved by distillation in the form of an azeotrope with the(meth)acrylate (II).

The catalyst(s) is(are) then introduced.

The reaction is carried out with generation of the alcohol R²OH, whichis removed by formation of an azeotrope with the (meth)acrylate (II), inorder to displace the equilibrium of the transesterification reaction.

Thus, the equilibrium of the transesterification reaction is displacedin the direction of the formation of compound (I).

Throughout the duration of the reaction, the pressure is adjusted inorder to maintain the temperature inside the reactor between 85 and 100°C.

If necessary, catalyst(s) is(are) supplied during the reaction.

When no further alcohol R²OH is formed, the reaction may be consideredto be complete.

The crude product obtained is then cooled and extracted from thereactor. It is generally in the form of a clear and very slightlycoloured liquid (colour less than 100 APHA).

Any excess of (meth)acrylate may then be removed by evaporation(so-called stripping operation), so as to isolate compound (I) from thereaction medium, generally in the solid state: thus, the1-ethylimidazolidyl-2-one acrylate is a white crystalline solid having amelting point equal to 43° C., which is soluble in the cold state inketones, alcohols, aromatic hydrocarbons and water, insoluble in thecold state in saturated hydrocarbons and which precipitates at 0° C.from ethyl acrylate. 1-Ethylimidazolidyl-2-one methacrylate is a whitecrystalline solid having a melting point equal to 47° C., possessing thesame solubility properties as the preceding compound. At the end of thestripping operation, the crystalline solid product may in addition bepurified by washing with a light alcohol such as methanol and/or with apetroleum ether, followed by filtration and drying.

The isolation of compound (I) may also be carried out by partialstripping of the (meth)acrylate (II), followed by crystallization at asufficiently low temperature (preferably of less than or equal to 0° C.)and for a sufficiently long period (which may be up to 15 hours), andthen filtration followed by the purification steps described above.

Finally, another method for isolating compound (I) from the solutioncontaining it consists of carrying out an extraction with water,followed by decantation, stripping of the (meth)acrylate and thepurification steps described above.

EXAMPLES

The following examples illustrate the present invention without,however, limiting the scope thereof.

The following abbreviations are used therein:

MMA: methyl methacrylate HEIO: 1-(2-hydroxyethyl)imidazolidyl-2-oneEIOM: 1-ethylimidazolidyl-2-one methacrylate MEHQ: monomethyl ether ofhydroquinone PTZ: phenothiazine Li(acac): lithium acetylacetonateCa(acac)₂: calcium acetylacetonate DBTO: dibutyltin oxide

Examples 1 to 3

Into a jacketed 630-litre stainless steel reactor supplied with athermofluid, equipped with a mechanical stirrer and surmounted by adistillation column (diameter 250 mm, height 4 m), filled with a PALLpacking and surmounted by a reflux head, are introduced:

150 kg of HEIO;

461 kg of MMA; and

0.2 kg of PTZ (polymerization inhibitor).

The column is stabilized by introducing into the reflux a solution ofMEHQ at 0.1% by weight in MMA.

The reaction mixture is dried by azeotropic distillation of the watercontained in the reagents (the azeotrope being formed between the MMAand the water) under a pressure of 400 mmHg (the temperature at the topof the column is 77° C.).

When the drying step is complete, the catalyst(s) is(are) introduced andadditional methyl methacrylate is added in order to maintain theMMA/EIOM molar ratio at its initial value of 4/1.

Throughout the duration of the reaction, the pressure is adjusted inorder to maintain the temperature in the reactor at 85° C.

The methanol formed by the reaction is removed in the form of anazeotrope with the MMA.

The reaction is complete when the temperature at the top of the columnno longer falls towards that of the azeotrope, in total reflux, at theoperating pressure.

The crude product is then cooled and analysed by HPLC.

The colour of the crude product is an important factor. It should be asfaint as possible.

Examples 1 to 3 of the following Table A were all performed under theabove conditions, by varying the nature of the catalyst(s). Example 2,outside the scope of the invention, was performed for the sake ofcomparisons: the catalyst does not contain compound (a).

It is therefore seen that the EIOM yields are comparable for Examples 1to 3. Nevertheless, the catalyst of Comparative Example 2 gives a finalproduct having a strong colour.

TABLE A Exam- Catalyst and mol % Duration of the Colour of the crude plerelative to the HEIO reaction in hours Product in APHA 1 Li(acac): 0.1510 41 2 Ca(acac)₂: 0.15 10 100 (comp.) 3 Li(acac) and Ca(acac)₂ 8 740.15 and 0.10 (respectively) Composition of the crude product Exam- (%by mass) ple MMA % HEIO % EIOM % 1 57.8 1.2 33.3 2 58.7 1.4 35.7 (comp.)3 58.4 1.1 34.5

Examples 4 to 9

Trials were carried out in a small jacketed glass reactor which ismechanically stirred and surmounted by a glass distillation column,containing a “multiknit” packing (efficiency of 8 theoretical plates)and provided with a reflux head.

The general conditions are identical to those of Examples 1 to 3, theonly exception being the MMA/HEIO molar ratio which is now 3.5/1(instead of 4/1 previously).

Examples 5, 6 and 7, outside the scope of the invention, were performedfor the sake of comparison: their catalysts do not contain compound (a).

The results are presented in the following Table B.

It is therefore seen that the catalysts of the Comparative Examples 5, 6and 7 free of compound (a) give a strongly coloured final product.

TABLE B Exam- Catalyst and mol % Duration of the Colour of the crude plerelative to the HEIO reaction in hours Product in APHA 4 Li(acac): 0.27.5 50 5 DBTO: 1.3 15 150 (comp) 6 Zr(acac)₂ 8 120 (comp.) 0.2 7Ca(acac)₂: 0.2 6 110 (comp.) 8 Li(acac) and Ca(acac)₂ 6.5 70 0.2 and 0.1(respectively) 9 Li(acac) and 7 80 Mg(OEt)₂ 0.2 and 0.1 (respectively)Composition of the crude product Exam- (% by mass) ple MMA % HEIO % EIOM% 4 50.2 1.0 40.8 5 52.9 0.6 49.6 (comp.) 6 51.5 0.3 44.5 (comp.) 7 51.81.7 38.7 (comp.) 8 50.7 1.2 40.2 9 50.2 1.8 39.2

What is claimed is:
 1. A process for the preparation of compound (I):

 wherein: R¹ is a hydrogen atom or a methyl group; and A represents astraight- or branched-chain alkylene group having from 2 to 5 carbonatoms; B represents a straight-chain alkylene group having 2 carbonatoms; by reacting at least one (meth)acrylate of formula (II):

 wherein: R¹ had the abovementioned meaning; and R² is a straight- orbranched chain alkyl group having from 1 to 4 carbon atoms; with aheterocyclic alcohol of formula (III):

 wherein A and B have the abovementioned meanings; in the presence of acatalyst comprising at least one compound (a) which is a chelate formedof lithium and of a 1,3-dicarbonyl compound.
 2. The process according toclaim 1, wherein the 1,3-dicarbonyl compound is: a β-ketonic acid ester,such as acetylacetic ester; or a 1,3-diketone, such as acetylacetone,3-methylacetylacetone, benzoylacetone, dibenzoylmethane,2,4-hexanedione, 3,5-heptanedione, 3-phenylacetylacetone,4,4,4-trifluoro-1-phenyl-1,3-butanedione,2,2,6,6-tetramethyl-3,5-heptanedione,1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione and1,1,1-trifluoro-2,4-pentanedione.
 3. The process according to claim 2,wherein compound (a) is lithium acetylacetonate.
 4. The processaccording to claim 1, wherein said (meth)acrylate of formula (II) ismethyl acrylate or methacrylate, and said heterocyclic alcohol offormula (III) is 1-(2-hydroxyethyl)imidazolidyl-2-one.
 5. The processaccording to claim 1, wherein the molar ratio of compound (a) to theheterocyclic alcohol of formula (III) is between 0.05 and 0.3%.
 6. Theprocess according to claim 1, wherein the catalyst further comprises atleast one compound (b) chosen from the group consisting of magnesiumalkoxide, sodium alkoxide, calcium alkoxide, calcium acetylacetonate,calcium oxide and calcium hydroxide.
 7. The process according to claim3, wherein the catalyst further comprises at least one compound (b)chosen from the group consisting of magnesium alkoxides, sodiumalkoxides, calcium alkoxides, calcium acetylacetonate, calcium oxide andcalcium hydroxide.
 8. The process according to claim 6, wherein themolar ratio of compound (b) to the heterocyclic alcohol of formula (III)is between 0.01 and 0.1%.
 9. The process according to claim 8, in whichthe molar ratio of compound (a) to the heterocyclic alcohol of formula(III) is between 0.05 and 0.3%.
 10. The process according to claim 1,wherein the process is carried out in the presence of at least onepolymerization inhibitor selected from the group consisting ofphenothiazine, hydroquinone, the monomethyl ether of hydroquinone,di-tert-butyl-para-cresol, para-phenylenediamine, TEMPO,di-tert-butylcatechol and at least one of the preceding enumeratedpolymerization inhibitors combined with a metal chelator.
 11. Theprocess according to claim 10, wherein the content of polymerizationinhibitor is between 0.05 and 0.5% by weight relative to the weight ofheterocyclic alcohol of formula (III).
 12. The process according toclaim 1, wherein the process is carried out in an anhydrous medium. 13.The process according to claim 1, wherein the process is carried out ata temperature of between 70 and 120° C.
 14. The process according toclaim 1, wherein the process is carried out at a pressure of between 0.3and 1 bar.
 15. The process according to claim 14, wherein the process iscarried out with bubbling air.
 16. The process according to claim 1,wherein the process is carried out in the presence of an excess of the(meth)acrylate of formula (II) or an excess of the heterocyclic alcoholof formula (III).
 17. The process according to claim 16, in which themolar ratio of the (meth)acrylate of formula (II) to the heterocyclicalcohol of formula (III) is greater than
 1. 18. The process according toclaim 5, wherein the molar ratio of compound (a) to the heterocyclicalcohol of formula (III) is between 0.05 and 0.15%.
 19. The processaccording to claim 8, wherein the molar ratio of compound (b) to theheterocyclic alcohol of formula (III) is between 0.01 and 0.05%.
 20. Theprocess according to claim 9, in which the molar ratio of compound (a)to the heterocyclic alcohol of formula (III) is between 0.05 and 0.15%.21. The process according to claim 13, wherein the process is carriedout at a temperature of between 85 and 100° C.
 22. The process accordingto claim 17, in which the molar ratio of the (meth)acrylate of formula(II) to the heterocyclic alcohol of formula (III) is between 1.1 and 7.23. The process according to claim 22, in which the molar ratio of the(meth)acrylate of formula (II) to the heterocyclic alcohol of formula(III) is between 2 and 5.